Electronic time delay relay



Aug. 25, 1959 J. P. REHAHN ELECTRONIC TIME DELAY RELAY Filed Feb. 9, 1955 msm marmo? N INVENTOR v JENs PETER REHAHN .l E v P A @T l- $2 Il Il w m N T mT\o N, Q EA m W Q mo 5o msm @Eo/o u 1 ATTORNEY United States Patent O 2,901,606 ELECTRONIC TllVIE DELAY RELAY Jens Peter Rehahn, Berlin, Germany, assignor to VEB Funkwerk Kopenick, Berlin-Kopenick, Germany [nl Application February 9, 1955, Serial No. 487,170

' s claims. (cl. 25o-27) The present invention relates to electronic time delay relays.

lt is an object of the present invention, to provide an electronic time delay relay wherein the time delay is practically not dependent on variations of feed voltage and tube emission.

With this and other objects in View which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawing, in which:

The only figure is a schematic circuit diagram illustrating a preferred embodiment of the present invention.

Referring now to the drawing, the device comprises a dual stability tube circuit 1, with some respects `similar to a flip-flop circuit. Contrary to the known circuit, however, the cathode voltages of tubes 2 and 3 differ from one another. The cathode of tube 2 receives a positive bias voltage 2', smaller than the operational voltage of the tube circuit. Its cathode being biased, the control Voltage of tube 2 may be positive or negative relative to the cathode. The cathode of tube 3 being not biased, the output voltage of the relay, may be picked up across the grid and the grounded cathode of tube 3, and be used for example to control a subsequent stage.

In neutral state, the grid of an electron tube 4, connected to the tube circuit 1 through a resistor 6, has the same potential as the cathode, i.e. the tube 4 is unblocked. Its inner resistance is in parallel to a capacitor 5 connected between resistor 6 and zero potential. With proper choice of the resistors 6, 7 and 13, the voltage applied to the grid of tube 2 is lower than the voltage 2 applied to the cathode of tube 2. This grid, therefore, is negatively biased and tube 2 is blocked. The potentiometer, formed by the anode resistor 10 of tube 2 and two resistors 11 and 12, connected across the operational voltage and the negative grid bias voltage 3 is chosen such, that with blocked tube 2, i.e. when no anode current flows in resistor 10, the voltage picked up at the junction point of resistors 11 and 12 and lead to the grid of tube 3 is with certainty such, that this latter tube is unblocked. In neutral state tubes 3 and 4 are unblocked and tube 2 is blocked.

If now tube 4 is blocked in order to energize the relay, the voltage across capacitor 5 increases. In accordance with the time constant of the RC-circuit formed by the network of resistors and condenser 5, the grid voltage of tube 2 rises until anode current starts to flow. The voltage drop across resistor 10 of potentiometer 10, 11, 12 increasing thereby, the grid voltage of tube 2 decreases. Hereby also the anode current in resistors 8, 9 in the anode circuit decreases, while the voltage at the junction point of resistors 8, 9, and thereby the grid voltage of tube 2 rises. This phenomenon, independently of further loading capacitor 5, continues until grid current in tube 2 starts to ow. Since anode current then starts to ow in resistor 10, the negative grid voltage of tube 3 becomes as high as to completely block this tube. In state of operation, therefore, tubes 3 and 4 ar'e blocked and tube 2 is unblocked.

By proper choice of resistors 6 and 7, the transition from one state into the other can be accomplished in a relatively short time. The voltage leaps` caused hereby at the anodes of tubes 2 and 3 can be picked up on the terminals 14 and 1S, respectively, and, after taking the derivatives, can be used as steering pulses. y

When tube 4 is again made to be unblocked, capacitor 5 discharges over the anode-cathode path of tube 4. As soon as the grid of tube 2 becomes negative with respect to the cathode, tubes 2 and 3 fall back again into the starting condition.

The time needed for this can be made Very short compared with the time of delay.

The time of delay can be found from wherein R is the equivalent resistance corresponding to the network, and U is the equivalent voltage across capacitor 5 with the capacity C. Ub is the grid bias voltage of the tube, in which the anode current is fallen down to a negligible small value. With constant capacity and constant resistance the time of delay t depends on the ratio Uk-Ub U wherein U is practically proportional to the operational voltage. With triodes applied Ub depends on the operational voltage. In order to keep as small as` possible the influence of a change of Ub which also occurs with a decrease of emission, Uk must be possibly large with respect to Ub. For the same reason, the moment of transition shall be within the steep slope of the curve of charge against time of the capacitor, i.e. when 1. 1n1Uk Ub:l

Since with variations of the primary voltage of the power supply the ratio of the operational voltage and 2' remains constant, the time delay is practically not iniluenced thereby. Measurements with a tentative device have proved that with a 10% change of the supply voltage the change of the time delay is smaller than 1%. Hereby in most cases stabilization of supply voltage becomes unnecessary whereby considerable savings can be obtained. Any number of electronic time delay relays according to the invention having different values of time delay may be switched in series by connecting the grid of tube 4 to terminal 16 of tube 3 of the preceding relay. Herewith, in consequence of the load dependency of normal, not stabilized circuit devices, also the ratio of the operational voltages and that of 2 is changed. Therefore it becomes necessary to choose the electric values of each stage according to the ratio of voltage as they exist after the response of the preceding stage, whereby, also in this case, variations of the feed voltage remain without influence.

The time delay of my invention differs from devices of the prior art, besides by other characteristics, by a dual stability tube circuit comprising two electron tubes, wherein the cathode of the tube following the input is on a positive potential and the grid of this tube is connected to one electrode of a capacitor in parallel with a switching device, for example an electron tube, the other capacitor electrode being grounded; the cathode of the other tube of said circuit being grounded such, that an output voltage may -be picked up across the grid 3 and the cathode of this tube and be used, for example, for controlling a subsequent stage. The switching device in parallel with the capacitor is operated by a grounded control Voltage source.

The time delay according to my invention-s advantageous as compared with time delay relays using glowdischarge lamps or thyratrons, in so far, as it is less dependent on temperature changes.

`I have described a preferred embodiment of my invention, but it is understood that this disclosure is for the purpose of illustration and that various omissions or changes in arrangements of parts, as well as the substitution of equivalent elements for those, herein shown and described may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. An electronic time delay apparatus comprising a ip-op circuit including a rst electron tube and a second electron tube, a source of anode potential, resistive circuit means connecting the anodes of said tubes to said source of potential, a direct current connection from the control grid of each tube to the anode resistive circuit of the other tube applying a high positive potential to the control grid of said second tube from the plate of said rst tube when said rst tube is non-conducting, means for maintaining the cathode of the rst electron tube at a considerable positive potential yet lower than the potential of the anode of said lirst electron tube, and maintaining the cathode of the second tube at a much lower potential than that of the cathode of said iirst tube, a switching circuit comprising a third electron tube, a capacitor connected between the cathode and the anode of said third tube, means including a resistor for applying a charging potential to the anode of said third tube and said capacitor, a direct current coupling from the control grid of said irst tube of said flip-flop circuit to the anode of said third tube, means for maintaining said ,iirst tu=be non-conductive and said second and third tubes normally in a conductive state, and means for applying control potentials to the control elect-rode of said third tube for rendering it non-conductive and thereby applying potential to said control grid of the first tube which renders it conductive and causes said third tube to become non-conductive, and means for obtaining output voltages from said ip-llop circuit which are delayed with respect to said control potentials.

' 2. An electronic time delay apparatus comprising a flip-Hop circuit including a iirst electron tube and a second electron tube, a source of anode potential, resistor means connecting the anodes of said tubes to said source of potential, direct current connection from the control grid of each tube to the anode of the other of said tubes, means for maintaining the cathode of said first of said electron tubes at a relatively high positive potential and the cathode of said second tube at a relatively low potential, a switching circuit comprising a third electron tube, a capacitor connected between the cathode and the anode of said third tube, means including a resistor for applying a charging potential to the anode of said third tube and the capacitor, a direct current resistive coupling from the control grid of said irst tube of the flip-hop circuit to the anode of said third tube, means for maintaining said first tube non-conductive and said second and third tubes normally in the conductive state, and means for applying control potentials to the control electrode of said third tube for rendering it non-conductive and thereby applying a potential to the control grid of said rst tube which renders it conductive and causes the third tube to become non-conductive, and means for obtaining output voltages from said ip-iiop circuit which are delayed with respect to the control potentials.

3. An electronic time delay apparatus comprising a ilip-op circuit including a rst electron tube and a second electron tube, a source of anode potential, resistor means connecting the anodes of said tubes to said source of potential, direct current connection from the control grid of each tube to the anode of the other of said tubes, means for maintaining the cathode of the first of said electron tubes at a considerable positive potential relative to but lower than that of the anode potential, a switching circuit comprising a third electron tube, a capacitor connected between the cathode and the anode of said third tube, the cathodes of the second and third tulbes being at zero potential, means including a resistor for applying a charging potential to the anode of the third tube and the capacitor, a direct current resistive coupling from the control grid of said rst tube of said flip-dop circuit to the anode of the third tube, means for maintaining said rst tube non-conductive and said second and third tubes normally in the conductive state, and means for lapplying control potentials to the control electrode of said third tube for rendering it non-conductive and thereby applying a potential to the control grid of said rst tube which renders it conductive and causes the second tube to become non-conductive, and means for obtaining output voltages from said flip-flop circuit which are delayed relative to the control potentials.

References Cited in the file of this patent UNITED STATES PATENTS 2,158,285 Koch May 16, 1939 2,262,838 Deloraine et al. Nov. 18, 1941 2,266,401 Reeves Dec. 16, 1941 2,414,486 Rieke Jan. 21, 1947 2,432,453 Skellett Dec. 9, 1947 2,588,925 Hecht Mar. 11, 1952 2,612,560 Rea sept. 3o, 195* 

